control valves versus self acting regulators 1

[Refining1]

Hi, While sizing and selecting a control valve I understand that the term Cv is used and this is calculated using ISA 75.01 standard for valve sizing.However for a regulator there are no such standards and capacity of a regulator is determined from the flow rates published at certain droop. If both regulators and valves are used on similar applications then why two different sizing methodology? Any thoughts

 

[Compositepro]

A control valve does not include any controller. Cv is the information one needs in order to select a control valve. A regulator has an integral controller which is what causes droop. Droop is the information that one needs to select a regulator.

 

[ScottyUK]

A proprotional controller introduces droop; an integral controller eliminates it. Most mechanical regulators don't have an integrating elelment.